It is known to use polymer additives in fuel compositions and in lubricating oil compositions, including the use of hydrocarbon-polymer-based products as detergent or dispersant additives. U.S. Pat. No. 3,219,666, for example, discloses oil-soluble acylated nitrogen compositions useful as dispersants in lubricating oil compositions prepared by the reaction of hydrocarbon-substituted succinic acid producing compounds (e.g., polyisobutene-substituted succinic anhydrides) with amines such as alkylene polyamines.
U.S. Pat. No. 5,229,022 teaches fuel and lubricating oil additives comprising ethylene-alpha-olefin copolymers terminally substituted with mono- or dicarboxylic acid producing moieties. The acid-substituted polymer can be further reacted with nucleophilic reagents such as amines, alcohols, and metal compounds to give other materials useful as additives, such as dispersants.
EP-A-490454 teaches alkenyl succinimide derivatives useful as dispersant additives, wherein the alkenyl group is derived from a terminally unsaturated atactic propylene oligomer. The succinimide derivative is formed by reacting the succinated oligomer with a C.sub.1 -C.sub.50 amine.
Polymer additives capable of providing more than one function are also known. U.S. Pat. No. 4,863,623, for example, discloses a multifunctional lubricant additive which is a VI improver, a dispersant, and an anti-oxidant when employed in a lubricating oil composition. The additive is a reaction product comprising an ethylene copolymer or terpolymer (molecular weight of 5,000 to 500,000) of a C.sub.3 to C.sub.10 alpha-monoolefin and optionally a non-conjugated diene or triene (e.g., EPDM) on which has been grafted an ethylenically unsaturated carboxylic acid material (e.g., maleic anhydride) which is then further derivatized with an amino-aromatic polyamine compound selected from certain N-arylphenylenediamines, aminothiazoles, aminocarbazoles, amino-indazolinones, aminomercaptotriazoles and aminoperimidines.
U.S. Pat. No. 5,182,041 discloses the reaction product of a polyolefin (molecular weight of 300 to 3,500) of a C.sub.2 to C.sub.10 alpha-monoolefin and optionally a non-conjugated diene or triene which has been reacted with an ethylenically unsaturated carboxylic acid material and then further derivatized with an amino-aromatic polyamine like those disclosed in the '623 patent of the preceding paragraph. The reaction product is disclosed to impart dispersancy and anti-oxidant properties to lubricating oil compositions.
U.S. Pat. No. 4,248,725 discloses additives having both dispersant and antioxidant activity in lubricating oil compositions. The additives are produced by reacting a dispersant having free&gt;N--H groups (e.g., a substitute succinimide) with an aldehyde and a compound having antioxidant activity and capable of condensing with the &gt;N--H groups in the dispersant and the aldehyde. Mononuclear and polynuclear substituted phenols and secondary aromatic amines are disclosed to be suitable antioxidants.
There is a continuing need to develop new additives for fuel and lubricating oil compositions, especially additives which can effectively impart more than one property. An advantage of multifunctional additives to the formulator is that two or more discrete additives can be replaced with a single additive, thereby avoiding or minimizing the incompatibility problems and adverse interactions which can often accompany the use of several monofunctional additive components in a composition.